1. Field of the Invention
The present invention relates to a roller for removing or imparting shrinkages on a metal or cloth sheeting, and more particularly to a roller for such use, the roller having a surfacial layer whose diameter progressively diminishes from its central portion toward the opposite ends, and being supported on an arched shaft rotatively, thereby ensuring that the sheeting is stretched or shrinked without the possibility of leaving permanent deflection therein.
2. Description of the Prior Art
To remove or impart shrinkages on metal or cloth sheeting, the common practice is to use a barrel-shaped roller supported by a straight shaft. The barrel-shape roller has a cross-section of symmetrically arched profiles like a beer barrel. Such barrel-shaped rollers are useful for carrying a thin sheet thereon without the possibility of slipping. When a sheet runs on the arched surfaces of the roller the contact therebetween is minimized so as not to produce a permanent set on the sheet.
There is a case where two barrel-shaped rollers are used in pair as a pinch roller unit. When tapes of different thicknesses are passed side by side therethrough with thin tapes inside and thick tapes outside, they are fed out at a constant rate irrespective of the differences in thickness. This requires that the same number of winders having different r.p.m. as that of the tapes are used.
There is another roller unit which comprises an arched roller having a constant cross-sectional area throughout its length, which is carried on an arched shaft. When a sheet material is passed on this roller a force acts on the sheet crosswise, that is, axially of the shaft. When the sheet runs toward the peripheral edges of the roller it is subjected to an outward force, whereas when the sheet runs toward the center it is subjected to an inward force. In the former case the sheet is outwardly extended, and in the latter case it shrinks. This is effective to remove and impart shrinks on the metal sheet. However, the known arched roller must be provided with any means for keeping the sheet material on the roller, otherwise it would slip off. To this end the barrel-shaped roller is used to help the arched roller.